This invention relates to an appliance comprising at least an electric motor and a circuit for driving the electric motor, which circuit comprises a first pulse switch for generating a first pulse, first switching means with a holding capability to perform a first switching function in response to the first pulse, and main switching means for switching the electric motor, the first switching function being adapted to control the main switching means.
Such an appliance may take the form of, for example, a food processor, in which the electric motor is coupled to a rotatable cutter. A food processor can be used for food processing, such as for example vegetable shredding.
An appliance at least comprising the electric motor and the circuit for driving the electric motor is generally known, the first pulse switch being frequently constructed by means of a push-button. Such a push-button switch usually comprises a fragile spring contact, which spring contact in the case of energization is closed briefly to generate a pulse. Since the first switching means have a holding capability these switching means are responsive to the first pulse generated by the first pulse switch to perform the first switching function for at least a first time interval, which switching function causes the electric motor to be switched on via the main switching means. The main switching means have been arranged between the first switching means and the electric motor because the electric motor is generally powered from an alternating voltage source and the drive circuit is powered from a direct voltage source.
A disadvantage of such an appliance is that in the event of a defect in the first pulse switch or in the first switching means, the electric motor is often switched on. When the appliance takes the form of, for example, a food processor the electric motor thus switched on may give rise to a hazardous situation owing to the rotatable cutter which is coupled to the electric motor.